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Osteoglossum bicirrhosum
The silver arowana, Osteoglossum bicirrhosum, sometimes spelled arawana, is a freshwater bony fish of the family Osteoglossidae, commonly kept in aquaria. The term "Osteoglossum" means "bone-tongued" and "bicirrhosum" means "two barbels" (from the Greek language). Description This species is found in the Amazon River basin and in the Rupununi and Oyapock Rivers in South America as well as in still waters in Guyana. This fish has relatively large scales, a long body, and a tapered tail, with the dorsal and anal fins extending all the way to the small caudal fin, with which they are nearly fused. It can grow to a maximum size of around 36 inches or more in captivity. In the wild, it has been known to reach over 48 inches in length. Unlike the Black Arowana, Silver arowanas have the same coloring throughout their lifespan. The species is also called monkey fish because it of its ability to jump out of the water and capture its prey. It usually swims near the water surface waiting for potential prey. Although specimens have been found with the remains of birds, bats, and snakes in their stomachs, its main diet consist of crustaceans, insects, smaller fishes and other animals that float on the water surface, for which its draw-bridge-like mouth is exclusively adapted for feeding. Arowana are sometimes called Dragon Fish by aquarists because their shiny armor-like scales and double barbels are reminiscent of descriptions of dragons in Asian folklore. Conservation status The Silver Arowana is currently not listed on any CITES appendix CITES Appendices nor on the 2004 IUCN Red List.IUCN Red List It is one of the most popular ornamental fish from South America, however, and therefore its conservation status merits attention.International meeting on ornamental fish boosts regional conservation and sustainable resource management initiatives (WWF) As reported by Environment News Service in August 2005, shared use of the Silver Arowana population was a cause for a dispute between Brazilian and Colombian authorities. Juvenile Silver Arowanas are caught in Colombia for sale as aquarium fish, while the people of Brazilian Amazonia catch adult fish for food. A sharp drop in the number of arowanas had caused Brazilian authorities to prohibit fishing of them between September 1 and November 15; the Colombians, on their part, would prohibit capturing them between November 1 and March 15. Brazil, Colombia at Odds Over Silver Amazon Fish. A meeting between the representatives of the Amazon Basin countries in August 2005 was meant to discuss the dispute. The Silver Arowana is often kept as a pet, being considered an accessible substitute for the Asian arowana, which is listed on CITES Appendix I and is therefore difficult and expensive to obtain legally. Aquarium fish Aquaria To keep one of these large fish, a properly sized aquarium is important. The minimum recommendable tank size for one adult Silver Arowana is 72 inches x 24 inches x 24 inches, or approximately 180 gallons. At no time should an arowana be kept in a tank that is narrower than the fish is long! A young specimen can be kept in a smaller tank, but as it grows a larger tank will be necessary to prevent deformities and to ensure the maximum length and life span of the animal. Any aquarium housing an arowana should be tightly covered because of these fishes' jumping behavior. Water conditions Silver Arowana prefer soft water with a pH level between 6.0 and neutral. Strong filtration is necessary for these large carnivores. Commercially available black water additives can help simulate the Silver Arowana's natural habitat, although they can adapt to most water supplies and thrive. A 25-30% water change, siphoning waste and other detritus, is necessary 1-2 times every week to maintain excellent water conditions. The water temperature should range from 24°C (75°F) to 28°C (82°F), with the ideal about 26°C (79°F). (reduced pigmentation). From The 6th "Pramong Nomjai Thaituala" Thailand Tropical Fish Competition 2007.]] Feeding Silver Arowana may be offered meaty foods such as insects, shrimp, fish, beef heart, frogs, etc, though it is best to feed the Arowana a brand of floating pellet food that has been specifically processed for fish of this type. There are several types of food on the market from some of the larger name brand makers of fish products that are made with this species in mind. Feeding the Arowana in this manner will help avoid dropeye, a condition in which one of the eyes are turned downward. In the wild, the Arowana spends most of its life scanning the water surface for prey, but it will learn in an aquarium environment to look downwards for food that sinks to the bottom of its tank. Over time, one eye will permanently droop downwards. The origin of dropeye remains uncertain however, with some aquarists who have only ever fed floating pellets having noticed it happening as a jumping arowana crashed into the tank lid - also not encountered in the wild. Another condition that can develop is "cloudy eye"; one or both of the eyes become scratched when the Arowana turns itself sideways to collect food from the bottom, causing them to cloud over. The cloudy eye condition is treatable, while the drop eye condition is not. Keeping an Arowana almost exclusively on a pellet diet will not only provide the fish with a well balanced meal, it is more cost effective and will generally prevent health issues. Many aquarists recommend against live feeder fish because these are often raised in poor conditions and are capable of transmitting diseases to predatory fish. Other risks include injury to the Arowana either while attempting to catch the feeder fish, or while swallowing. Mealworm exoskeletons are sometimes difficult for young Arowana to digest, so they are best avoided. Tankmates Silver Arowana can be kept with other freshwater fish as long as they are too large to fit in the arowana's mouth and can tolerate the arowanas active-swimming lifestyle. Many people like having more than one Arowana in the tank; in this case, hobbyists recommend keeping at least 5 to 6 in the tank at a time because Silver Arowana are very aggressive towards each other. See also *List of freshwater aquarium fish species References See also * Arowana * Asian arowana References * * * Dawes, John; Chuan, Lim Lian; & Cheong, Leslie, eds (1999). Dragon Fish, The. Kingdom Books England. Category:Osteoglossidae Category:Fauna of Guyana cs:Arowana dvojvousá de:Arowana fr:Osteoglossum bicirrhosum nl:Arowana ja:シルバーアロワナ pt:Aruanã-prateado fi:Aravana th:ปลาตะพัดอเมริกาใต้สีเงิน